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Expert Answer

Cachexia is a condition in which the body consumes excess energy. There is accelerated loss of fat stores and then consumption of proteins such as skeletal muscle.

Cachexia is best known as a disease of cancer patients, but it is seen in patients with chronic infection, AIDS, heart failure, rheumatoid diseases and chronic obstructive pulmonary disease. Nearly half of patients with cancer that has spread to organs other the original site of disease (metastatic disease) have cachexia.

Loss of appetite or anorexia is often associated with cachexia, especially cachexia of malignancy.

Contrary to what many think, this is not a disease caused by starvation. The loss in weight and body mass is driven by a metabolic disease manifested by increased energy consumption. As a result, aggressive feeding and caloric replacement are not adequate treatments. Extremely aggressive efforts are to be discouraged. There are studies that suggest that forced tube feeding or intravenous feeding (known as hyperalimentation) can actually increase the risk of infection and death.

Cachectic patients generally do not respond well to anti-cancer therapies. In one National Cancer Institute-sponsored study, weight loss of greater than 5 percent from baseline was a predictor of poor outcome, independent of cancer stage, type of cancer, and patient performance status. Performance status is a rating of a patient's ability to walk and independently handle the activities of daily living, such as dressing or hygiene.

Studies demonstrate that cachexia is the direct cause of death in a small number of cancer patients (1 to 2 percent). This is akin to the body running out of fuel or extreme malnutrition. More commonly, the person has lost a great deal of immune function and becomes susceptible to infection, or cachexia can lead to metabolic disorders that can cause heart rhythm disturbances. There are no good estimates as to how often this occurs.

Cancer cachexia appears to be caused by chemicals given off by the tumor or by the patient's immune system that is trying to combat the tumor. These chemicals are called cytokines. Some cytokines have also been found to cause depression, which can also, of course, cause loss of appetite, worsening the condition. When there is effective treatment of the cancer, symptoms of cachexia decrease.

A number of agents have been studied, not as treatment of the cancer, but as a treatment of cachexia of malignancy. These include melatonin, thalidomide, cannabinoids and androgenic steroids.

Only the corticosteroids, such as dexamethasone, and the progestational agents, such megesterol acetate, have proven of benefit in treatment of the loss of appetite. While a number of studies show corticosteroids and progestational agents cause an increase in appetite and even weight gain, these studies have not shown that they improve quality of life or survival.

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